The correct option is A Morgan
The chromosomal theory of inheritance identified that chromosomes are the genetic material responsible behind Mendelian inheritance. It was observed by Sutton and Boveri. They argued that the pairing and separation of a pair of chromosomes result in the segregation of the pair of factors that they carry.
However, the experimental verification of chromosomal theory of inheritance was given by Morgan based on his experiments conducted on Drosophila melanogaster.
Bateson gave the term Genetics to Mendel’s experiments and he, along with Punnett, co-discovered the gene linkage.
Punnett, a British geneticist, had introduced the concept of punnett square for finding out the probability of all possible genotypes of offspring in a genetic cross.